Low levels of vitamin D and high levels of parathyroid hormone are associated with increased mortality according to a new study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology and Metabolism (JCEM). The study also indicates that the potential impact of remediating low vitamin D levels is greater in African Americans than Caucasians because vitamin D insufficiency is more common in African Americans.

People with higher blood levels of vitamin D live significantly longer than people who have low blood levels of the vitamin.

Vitamin D is naturally synthesized by the body upon exposure to the ultraviolet radiation from sunlight. Health experts say that light-skinned people can produce enough vitamin D from 10 to 15 minutes per day of sunlight on the face and hands, while dark skinned people need approximately twice that amount.

Women with blood levels of the vitamin lower than 15.3 nanograms per millilitre were more likely to die from causes such as heart disease and cancer, than women with higher levels (above 27 ng/ml).

For the past several years, there has been considerable interest in the role vitamin D plays in improving health and preventing disease. Low levels of vitamin D have been directly associated with various forms of cancer and cardiovascular disease. Most studies regarding the health effects of low vitamin D levels have been conducted on persons of European origin, but the current study examines the relationship between vitamin D and mortality in blacks and whites.

"We observed vitamin D insufficiency (defined as blood levels <20 ng/ml), in one third of our study participants. This was associated with nearly a 50 percent increase in the mortality rate in older adults," said Stephen B. Kritchevsky, PhD, Professor of Internal Medicine and Transitional Science at the Wake Forest School of Medicine, and lead researcher of this study. "Our findings suggest that low levels of vitamin D may be a substantial public health concern for our nation's older adults."

In this study, 2,638 Caucasians and African-Americans aged 70-79 years were asked to fast for 12-hours, after which a blood sample was collected to determine levels of vitamin D. Every six months study participants were contacted to ascertain their medical condition. This study determined the proportion of deaths among participants of with different vitamin D levels. In addition to many health factors, the time of year was also taken into account due to the seasonal effects on vitamin D. Researchers found that levels of vitamin D less than 30 ng/ml were associated with significantly increased all-cause mortality.

"We all know that good nutrition is important to overall health and our study adds to a growing body of literature that underscores the importance of vitamin D and indicates that poor vitamin D nutrition is wide-spread," said Kritchevsky. "The good news is it's easy to improve vitamin D status either through increased skin exposure to sunlight or through diet or supplements."

April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.